Crane recovery of an aircraft is a preferred method for many airports. However some aircraft do not have a strong point which is both accessible from above, and is suitably configured to attach a lifting sling or crane hook.
One solution to this problem is to inflate an airbag under a wing of the aircraft. However for large aircraft this may cause instability concerns, particularly if the airbag is wet. Also the tendency of the wing to bend as the lifting occurs increases the total height of the airbag lift required, thereby exacerbating the problem.